The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
A waste heat recovery system may be applied to an exhaust system of a vehicle to recover energy that would be otherwise emitted from the exhaust system. The waste heat recovery system may convert thermal energy obtained from the exhaust system to electrical energy, which may then be used operate electrical components and/or motor(s) of the vehicle.
A waste heat recovery system may include, for example, a heat exchanger or coil in which a coolant passes. The coil may be located within and receive thermal energy from an exhaust system. The coolant is then passed through an expander, where thermal energy within the coolant may be converted to mechanical energy. The coolant is then pumped through and further cooled by a condenser prior to again being cycled through the heat exchanger.
In addition to having the heat exchanger, the exhaust system may also include a catalytic converter. The catalytic converter may be located, for example, upstream from the heat exchanger and be used to reduce emissions of an internal combustion engine (ICE). For example, a three-way catalytic converter reduces nitrogen oxide, carbon monoxide and hydrocarbons within an exhaust system. The three-way catalytic converter converts nitrogen oxide to nitrogen and oxygen, converts carbon monoxide to carbon dioxide, and oxidizes unburnt hydrocarbons (HC) to produce carbon dioxide and water.
An average catalyst light-off temperature at which a catalytic converter typically begins to function is approximately 200-350° C. As a result, a catalytic converter does not function or provides minimal emission reduction during a warm up period that occurs upon a cold startup of the ICE. Exhaust system temperatures are less than the catalyst light-off temperature during an engine cold start. During the warm up period, HC emissions may not be effectively processed by the catalytic converter.